Apparatus for defining orientation of an alignment layer in a pixel unit of an LCD device and the method thereof

ABSTRACT

An apparatus for defining orientation of an alignment layer in a pixel unit of an LCD device is provided. The pixel unit includes a glass substrate having an outer surface provided with the alignment layer treated by photolithographic masking and rubbing operation. The apparatus includes a conveyor belt for feeding the alignment layer; a vapor-generating device disposed above the conveyor belt in such a manner that the alignment layer is formed with a plurality of vapors when passed underneath the vapor-generating device; a light source for providing light beams into the vapors on the alignment layer; and an image catcher for fetching an image data formed on the alignment layer by virtue of light reflection and refraction of the vapors hanging on the alignment layer.

FIELD OF THE INVENTION

The present invention generally relates to an apparatus for defining orientation, and more particularly to an apparatus for defining orientation of an alignment layer in a pixel unit of a liquid crystal display (LCD) device and the method thereof.

BACKGROUND OF THE INVENTION

In manufacturing an LCD device, liquid crystals are injected in a sealed space confined by two substrates to form a liquid crystal layer that generally permits light beams to pass therethrough in a normal state. The liquid crystals are normally in a liquid state rather than a solid state. Since they are very sensitive to heat, their orientation changes when an appropriate voltage is applied thereto so as to control light passage, thereby converting the liquid crystal layer into non-transparent or half-transparent state, which consequently results in an image display. Generally, an alignment layer is fabricated on the glass substrate by the photo printing technique in order to set the pre-tilt angles of the orientation of the liquid crystal molecules in the liquid crystal layer. The alignment layer can be made from natural polymer or artificial polymer (polymide), which may have to be treated in advance by photolithographic masking and rubbing operations in order to manipulate the orientation of nearby liquid crystal molecules. Prior to assembly, the substrate (with the alignment layer thereon) must undergo several testing and checking operations so that its defect can be found and/or the orientation of the substrate can be defined.

Typically, testing and checking operations of the glass substrate 1 are accomplished manually as shown in FIG. 1. The glass substrate 1 is held by one person, and is passed adjacent to a vapor-generating device 31 in such a manner to form a plurality of vapors 32 on the alignment layer 10 by virtue of its initial low temperature. A light projector 22 is then used to direct light beams onto the alignment layer 10. In order to define the orientation of the alignment layer 10 and/or find out the defects of the alignment layer 10, the reflection and refraction of light caused by the vapors hanging on the alignment layer 10 are observed by naked eyes of a tester 4 by changing several viewing angles with respect to the glass substrate 1.

Some drawbacks of the above testing method are as follow:

-   -   (i) it is time-consuming and laborious to conduct the testing         operation manually. The goal of mass production of the glass         substrate is therefore hard to achieve.     -   (ii) The resultant orientation of the alignment layer is not         uniform because the procedure of defining orientation of the         alignment layer is unduly depends on different personal         experience and skills of an operator.     -   (iii) Several defected alignment layers must be discarded,         thereby increasing the cost of manufacture.

SUMMARY OF THE INVENTION

One object of the present invention is to provide an apparatus for defining orientation of the alignment layer in a pixel unit of an LCD device and the method thereof so as to eliminate the disadvantages resulting from the use and construction of conventional LCD devices.

According to one aspect of the present invention, a method is provided for defining the orientation of an alignment layer in a pixel unit of an LCD device. The pixel unit includes a glass substrate having an outer surface provided with the alignment layer that has been treated by photolithographic masking and rubbing operations in order to manipulate the orientation of nearby liquid crystal molecules. The method accordingly includes the steps of: (i) forming vapors on an outer surface of the alignment layer; (ii) providing light beams onto the alignment layer; (iii) fetching an image data formed on the alignment layer by virtue of light reflection and refraction in the alignment layer; and (iv) inspecting the image data to define the orientation of the alignment layer [07] In another aspect of the present invention, an apparatus is provided to define the orientation of an alignment layer in a pixel unit of an LCD device. The pixel unit includes a glass substrate having an outer surface provided with the alignment layer that has been treated by photolithographic masking and rubbing operation in order to manipulate the orientation of nearby liquid crystal molecules. The apparatus accordingly includes a conveyor belt for feeding the alignment layer; a vapor-generating device disposed adjacent to and above the conveyor belt in such a manner that an outer surface of the alignment layer is formed with a plurality of vapors when the alignment layer is passed underneath the vapor-generating device; a light source for providing light beams into the vapors hanging on the alignment layer; and an image catcher for fetching an image data formed on the alignment layer by virtue of light reflection and refraction of the vapors on the alignment layer so as to define the orientation of the alignment layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many attendant advantages of the present invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, of which:

FIG. 1 is a schematic view, illustrating testing operation of the orientation of an alignment layer on the glass substrate of a pixel unit in an LCD device according to the conventional method;

FIG. 2A shows the apparatus and the method according to the present invention for defining the orientation of an alignment layer in a pixel unit of an LCD device;

FIG. 2B shows another apparatus and method according to the present invention for defining the orientation of an alignment layer in a pixel unit of an LCD device;

FIG. 3A is a block diagram, illustrating the steps of defining the orientation of the alignment layer in the pixel unit of the LCD device according to one embodiment of present invention; and

FIG. 3B is a block diagram, illustrating the steps of defining the orientation of the alignment layer in the pixel unit of the LCD device according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It is noted that same reference numerals have been used to denote similar elements throughout the drawings and specification.

Referring to FIG. 2A, the preferred embodiment of an apparatus of the present invention is shown to include a conveyor belt 20, a vapor-generating device 21, a light source 22 and an image catcher 23. The present apparatus is used for defining orientation of an alignment 10 in a pixel unit of an LCD device. The pixel unit generally includes two glass substrates 1 (only one is shown in FIG. 2A) and a liquid crystal layer (not shown) sandwiched therebetween. The alignment layer 10 is generally fabricated on the glass substrate 1, and has been treated by photolithographic masking and rubbing operations in order to manipulate the orientation of nearby liquid crystal molecules in the liquid crystal layer. Because fabrication of pixel units are well known in the art, a detailed description thereof is omitted herein for the sake of brevity.

The vapor-generating device 21, the light source 22, and the image catcher 23 are disposed along a straight line. The conveyor belt 20 is disposed below the vapor-generating device 21 for feeding the glass substrate 1 along a passing route (X) such that after passing underneath the vapor-generating device 21, an outer surface of the alignment layer 10 is formed with a plurality of vapors due to its initial lower temperature. The vapor-generating device 21 may include a cooling element 211 which is adapted to lower the temperature of the alignment layer 10 in such a manner to form the plurality of the vapors on the alignment layer 10, and two partitions 213 disposed at opposite side of the cooling member 211. The partitions 213 cooperatively define a cooling chamber facing the passing route (X) of the conveyor belt 20. Alternatively, the vapor-generating device 21 may include a humidity controller 212, which is adapted to increase the temperature of the alignment layer 10 in such a manner to form the plurality of vapors on the alignment layer 10, and two partitions 213 disposed at opposite sides of the humidity controller 212. The partitions 213 cooperatively define a hot chamber facing the passing route (X) of the conveyor belt 20. Since the humidity escapes only toward the passing route (X) of the conveyor belts 20, the light source 22 and the image catcher 23 disposed at the ambient surrounding thereof are not affected by the density of the cooling element 211 or the humidity of the humidity controller 212. Preferably, the humidity controller 212 is further formed with a plurality of outwardly projecting spouts 31 for supply of steam onto the alignment layer 10, thereby forming the vapors on the alignment layer 10.

The light source 22, preferably a light projector, is disposed at a distance away from the vapor-generating device 21, and projects light beams onto the alignment layer 10 as the latter travels forward. Under this condition, image data will be formed on the alignment layer 10 by virtue of light reflection and refraction of the vapors hanging on the outer surface of the alignment layer 10. The image catcher 23, being disposed adjacent to the light source 22, catches the image data reflected back from the alignment layer 10. The image catcher 23 can be charge-coupled devices (CCDs), which read the light beams and capture video or still images formed on the vapors, and includes a digital signal processor (DSP) 24 which processes the images and shows the resultant data on a display monitor 25. Under this condition, the operator 4, viewing the monitor 25, can determine the orientation of the alignment layer 10.

FIG. 2B shows another preferred embodiment of the present invention to have the construction similar to the previous embodiment. In this preferred embodiment, the image catcher 23 includes an image recognizing system 26 that is coupled to the DSP 24. The DSP is stored with a reference table and is adapted to compare the image data fetched by the image catcher 23 with respect to the reference table so that any defect of the alignment layer 10 can be identified.

A method is provided according to the present invention for defining the orientation of the alignment layer 10 in a pixel unit of an LCD device, which includes the steps shown in FIG. 3A. At step 31, the glass substrate 1 coated with the alignment layer 10 is disposed on the conveyor belt 20 which travels along the route (X) so as to feed the glass substrate 1 to a position nearby the vapor-generating device 21. Note that photolithographic masking and rubbing operations are conducted on the alignment layer 10 in order to manipulate the orientation of the nearby liquid crystal molecules in the liquid crystal layer of the LCD device. At step 32, after passing underneath the vapor-generating device 21, the upper surface of the alignment layer 10 is formed with a plurality of vapors by virtue of its initial low temperature. At step 33, the light projector 22 is used to provide light beams onto the alignment layer 10 such that image data can be formed thereon due to reflection and refraction of light from the vapors. At step 34, the image data is fetched by the image catcher 23 that includes a digital signal processor 24 for processing the image data in such a manner to display the resultant data on the display monitor 25. At step 35 a, the operator 4 defines the orientation of the alignment layer 10 on the basis of the resultant data.

Another embodiment of the present invention is provided for defining the orientation (or to find out drawback) of the alignment layer 10 in a pixel unit of an LCD device, which includes the steps shown in FIG. 3B. At step 35 b, the image catcher 23 includes an image recognizing system 26 that is stored with a reference table and that is adapted to compare the image data automatically with the reference table so as to provide a resultant data shown on the display.

The advantages provided by the apparatus and method according to the present invention for defining the orientation of the alignment layer in the pixel unit of the LCD device are as follows:

-   -   (i) the viewing angles for observing the image data provided by         the vapors formed on the alignment layer are adjusted         automatically and continuously so as to save the manpower,         thereby providing an effective testing speed.     -   (ii) Since image recognizing system is used to compare the image         data with the reference table stored therein and since human         errors caused by the naked eyes of the operator can be         eliminated, a precise orientation of the alignment layer can be         achieved.

As understood by a person skilled in the art, the foregoing preferred embodiments of the present invention is of illustrative rather than limiting thereon. It is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structure. 

1. A method for defining orientation of an alignment layer in a pixel unit of an LCD device, the pixel unit including a glass substrate having an outer surface provided with the alignment layer which has been treated by photolithographic masking and rubbing operations, the method comprising the steps of: (i) forming vapors on an outer surface of the alignment layer; (ii) providing light beams onto the alignment layer; (iii) fetching an image data formed on the alignment layer by virtue of light reflection and refraction of the vapors hanging on the alignment layer; and (iv) inspecting the image data to define the orientation of the alignment layer.
 2. The method according to claim 1, wherein said vapor forming operation in the step (i) is achieved by permitting the alignment layer to pass through a high temperature region.
 3. The method according to claim 1, wherein said vapor forming operation in the step (i) is achieved by permitting the alignment layer to pass through a relatively high humidity region.
 4. The method according to claim 1, wherein said vapor forming operation in the step (i) is achieved by spraying a predetermined amount steam onto the alignment layer.
 5. An apparatus for defining orientation of an alignment layer in a pixel unit of an LCD device, the pixel unit including a glass substrate having an outer surface provided with the alignment layer which has been treated by photolithographic masking and rubbing operation in order to manipulate the orientation of nearby liquid crystal molecules, the apparatus comprising: a conveyor belt for feeding the alignment layer; a vapor-generating device disposed adjacent to and above the conveyor belt in such a manner that an outer surface of the alignment layer is formed with a plurality of vapors when the alignment layer is passed underneath of said vapor-generating device; a light source for providing light beams into said vapors on the alignment layer; and an image catcher for fetching an image data formed on the alignment layer by virtue of light reflection and refraction of the vapors hanging on the alignment layer so as to define the orientation of the alignment layer.
 6. The apparatus according to claim 5, wherein said vapor-generating device includes a cooling element which is adapted to lower the temperature of the alignment layer in such a manner to form said plurality of vapors on the outer surface of the alignment layer.
 7. The apparatus according to claim 5, wherein said vapor-generating device further includes at least two partitions disposed at opposite sides of said cooling element and cooperatively defining a cooling chamber facing a passing route of said conveyor belt.
 8. The apparatus according to claim 5, wherein said vapor-generating device includes a humidity controller which is adapted to increase the temperature of the alignment layer in such a manner to form said plurality of vapors on the outer surface of the alignment layer.
 9. The apparatus according to claim 8, wherein said vapor-generating device further includes at least two partitions disposed at opposite sides of said humidity controller and cooperatively defining a hot chamber facing a passing route of said conveyor belt.
 10. The apparatus according to claim 9, wherein said humidity controller further includes a spout for supply of steam onto the alignment layer for forming said plurality of vapors.
 11. The apparatus according to claim 5, wherein said image catcher includes a data processor and a display which is linked to said data processor.
 12. The apparatus according to claim 5, wherein said image catcher includes an image recognizing system which is stored with a reference table and which is adapted to compare the image data automatically with the reference table thereby providing a resultant data shown on said display. 